Keyboard



FIG. 1 is a top view thereof;

FIG. 2 is a front view thereof;

FIG. 3 is a left side thereof;

FIG. 4 is a right side thereof; and,

FIG. 5 is a rear view thereof.

The design has a flat bottom that is unornamented and a view thereof is omitted from the specification. The subject matter shown in broken line represents unclaimed environmental structure which is shown for illustrative purposes and forms no part of the claimed design. 

The ornamental design for a keyboard, as shown and described. 